With the development of microprocessors, numerous processes and systems have been automated over the last three decades. As an example, automated clinical chemistry analyzers have developed to a point of substantial sophistication, with many such analyzers essentially being integrated collections of robots and other automatically controlled processes. The result is often a complex system including motion, fluid and temperature control along with photometers, ion selective electrodes and other sensing devices, all highly integrated and interdependent. An example of such a system is the SYNCHRON CX.RTM.7 automated clinical chemistry system available from Beckman Instruments, Brea, Calif., U.S.A.
However, as the complexity and integration of such systems has increased, the corresponding interdependence of the various subsystems can create problems with system integration, contributing to lengthened development time, complicated system modification, and increased difficulty in field service and maintenance. One aspect of such interdependence is often the common power supply that is provided throughout the system. Despite efforts to regulate such a power source for system-wide usage, and despite efforts the reduce or eliminate voltage drops and ground loops, the operation of one subsystem can often affect the operation of another subsystem through a common power bus. For example, a damaged "catch" diode across the coil of a solenoid can appear to be a variety of unrelated problems until the damaged diode is found.
Yet another aspect of such interdependence is the intra-system communication. Because of the complexity of these systems, a number of processors are used, some handling system-level tasks, such as system timing, and others handling the operation of specific functions, such as fluid probe movement and/or pump operation. Such intra-system communication has been achieved through the use of a common computer bus, including data, address and clock signals. Buses of this type quite typically are subject to noise and mechanical difficulties and, because such buses are transmission lines, changing loads can have an impact on digital wave form shapes transmitted along the buses. Further, by using these types of buses, conflict in the addresses of the various processors along the bus may be possible, further complicating the system design and integration.
Another difficulty in many prior art automated systems such as clinical chemistry analyzers is the use of a variety of motors in motion control, requiring corresponding development efforts for each motor. Further, despite the frequently large number of motion control motors used in advanced automated clinical chemistry analyzers, the fact that a motor that is experiencing a loss of performance, frictional binding or atypical loads is generally not known until the motor itself fails, causing down time for the analyzer and resulting in repair and service expense. Also, a motor that is operating near or at its functional limits may lead to intermittent failures that may be very difficult to detect during servicing.
Thus, there is a need for a system design that is easier to implement and where various automated devices that may be part of this system are less interdependent. There is also a need for a system that overcomes the prior-art difficulties encountered in intra-system communication. Also, there is a need for a system that tends to standardize the motion elements and which can detect motion element problems before the motion element, such as a stepper motor, fails.